Characterization and In Vitro digestibility of rice protein prepared by enzyme-assisted microfluidization: Comparison to alkaline extraction

• Published in: Journal of cereal science Vol. 56; no. 2; pp. 482 - 489
• Main Authors: Xia, Ning, Wang, Jin-Mei, Gong, Qian, Yang, Xiao-Quan, Yin, Shou-Wei, Qi, Jun-Ru
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2012; Elsevier
• Subjects: Biological and medical sciences; Cereal and baking product industries; Food engineering; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; In vitro digestibility; Microfluidization; Rice protein; Structural properties; Microfluidization; Rice protein; EM-RP; AE-RP; In vitro digestibility; Structural properties; In vitro digestibility; Cereal; Extraction; In vitro; Protein; Digestibility; Rice
• ISSN: 0733-5210; 1095-9963
• DOI: 10.1016/j.jcs.2012.06.008

Microfluidization followed by density-based separation was employed to extract protein from broken rice by disrupting protein-starch agglomerates. Follow-up enzyme treatments (amylase and glucoamylase) were performed to further improve the purity of the protein-rich fraction. High protein recovery (81.87%) and purity (87.89%) were obtained. The protein composition, solubility, structural properties, and in vitro digestibility of rice proteins prepared by enzyme-assisted microfluidization (EM-RP) and alkaline extraction (AE-RP) were compared. EM-RP was mainly composed of glutelin, which had low solubility and native structure. By contrast, large quantities of prolamin and globulin appeared in the AE-RP except glutelin, leading to the richness of glutamic acid/glutamine, leucine, aromatic and charged amino acids in the AE-RP. Compared to AE-RP, EM-RP showed higher digestibility due to the richness of glutelin (an easy-to-digest protein), as evidenced by higher nitrogen release during pepsin-trypsin digestion. The presence of prolamin (an indigestible protein) in AE-RP decreased protein digestibility although alkaline extraction improved its hydrolysis. These results suggest that enzyme-assisted microfluidization could be an effective technique to non-destructively and selectively extract rice glutelin. ► Microfluidization followed by density-based separation extracts rice protein. ► Carbohydrate-hydrolyzing enzyme treatments improve protein purity. ► Rice glutelin with native structure is non-destructively and selectively obtained. ► Rice glutelin shows better in vitro digestibility than alkali-prepared protein.